Centrifugal pump



' May 5, 1925. 1,536,573

- J. W. W. DRYSDALE ET AL CENTRIFUGAL PUMP Filed Nov, 5, 1925 2 Sheets-Sheet l Flc;

May 5, 1925; `1,536,573

J. W. W. DRYSDALE ET AL,

CENTRIFUGAL PUMP Filed Nov. 5, 1923 2 Sheets-Sheet 2 f//M if@ Patented May 5, 1925.

UNIATED STATES JOHN WHITEHEAD WIESON DRYSDALE ANDKJ'OHN YOUNG, 0F YOKER, NEAR GLAS-l PATENT OFFICE.

GOW, SCOTLAND, ASSIGNORS T0 DRfYSDALE & COMPANY, LIMITED, 0F YOKER, NEAR GLASGOW, SCOTLAND.

CENTRIFUGAL PUMP.

Application led November To all '107mm it may eminem:

Be it known that we, JOHN WHITEHEAD VILsoN DnYsnALn and JOHN YOUNG, both subjects of the King of Great Britain and lireland, both residing at Bon-Accord Works, Ferry Road, .Yoker, near Glasgow Scotland, have invented certain new and useful Improvements in Centrifugal Pumps; and we do hereby declare the following to be a full, clear", and exact description ofthe invention, such as will enable others skilled in the art to whichvit appertains tomake and use the same, reference being had to the accompanying drawings, and to letters or figures Of ieference marked thereon, which form a vpart Of thisspecification.

This invention relates to centrifugaly pumps and is intended to be applied to pumps employed for the withdrawal ofY liquid from vessels under high vacua such as surface vand jet condensers, vacuum evaporators, and the like, wherein the condensed vapour 'or liquid is withdrawn from the lowest point of the Vessel and pumped to any desired pressure above atmosphere.

The satisfactory Working Of acentrifugal pump under such conditions is the object of the present invention. For satisfactory working it is necessary to'secure freedom from air leakage at glands, a selfclearing action in regard to air locks, and the maintenance of a head of water over the impeller eye. With regard to the last vpoint,-it is often difficult under the conditions in question to secure any considerable head for the pump; and the ability of the pump to work with a low head is therefore of great importance. y

With the Object aforesaid in view the pump in accordance with the present invention is 'arranged to rotate on a vertical shaft. It is of the two-stage type, i. e. with two impellers in series. The irst-stage impeller is disposed at the lowest point in the pump,

' and is so arranged that the water from the 4vessel which is being drained or drawn from, tends togravitate into the eye of this impeller. The water passages of the. pump are so disposed as to prevent the formation of air locks by the flow in the said passages being always upwards from the first-stage im- A A or Fig. 1.

3, 1923. semi No. 672,573.

1 peller to the` final discharge outlet of the and connected by means of a balance pipe to the vessel which is being drained vor drawn from, the intention being that air drawn by the liquid from the said vessel shall be caught in the chamber and drawn back in'to the said vessel by the air pump which is employed for withdrawing air from the Vessel.

Further features Of advantage of our in- .vention are an annular nozzle or passage situated at and above the eye of the rststage impeller and *an 'air-extraction duct connecting the chamber above-mentioned withl this annular nozzle or passage, the object being the extraction, by way of the an` nular nozzle or passage, the chamber, and the balance pipe, of any air which collects by vortex action at the eye of the impeller.

In the carrying of the 'present invention r into effect the first-stage impeller-situated at the lowestV point in the pumpe-is arranged to dealwith the water at low absolute pres` -sure and to discharge this water to the second-stage impeller which is situated above the first-stage impeller, which secondstage impeller raises the pressure of the Water to any desired amount. This two-stage. arrangement has the advantage that the pressure at the eye of the second-stagev impeller may be, and in practice preferably is,

arranged to be above atmosphere, thus tending to prevent air leakage into the pump.

The accompanying drawings illustrate the carrying of the invention into effect in one convenient manner.

Fig. l is a vertical section through the pump.

Fig. 2 is a horizontal section On the line Fig. 3 is a front, elevation drawn to a reduced scale. s

The pump casing is constructed split in a vertical plane passing through the axis of rotation, thus allowing of the ready removal -Of therotating parts without disturbing pipe joints. The split is clearly shown in Fig. 2 and the difference in cross hatching in Fig. 1 makes clear the two parts into which the casing is divided, while the jointing is shown in Fig. 3.

a is the first-stage impeller and b L'thesecond-stage impeller. The discharge from the first-stage impeller to the second-stage impeller is by way of the duet c in the pump casing, which duct leads in an upwards and radially-inward direction from 'the .volute or discharge chamber of the first-stage impeller to the eye of the second-stage impeller (which is on the lower side of this impeller), there being no oae'nings, glands, -or `the like, in this duet which would allow of the induction of air.

The discharge from the volute g of the second-stage impeller to the discharge cham- 'f ber f ofthe pump is by way of the port 7L, i indicated by shading in Fig. 2.

The discharge chamber f is arranged `to `surround the shaft where the latter enters the pump casing at the top thereof, the' pressure of water discharge thus effectually 'sealing orl packing the pump against air 'leakage (which may be occasioned by the,A

improper adjustment of the packing gland).

d, (Z are'thc two discharge ports either of' which may he employed.' f

o is the suction port of the pump. This is connected by ythe pipe p to the vessel which is 'being drained or drawn from. The port c yis continued'by the passage or chamber 7c above and communicating with the eye of the` .first-stage impeller, which `iis on the upper side of thisl impeller.

, The locationsof the two impelleI-S and the positions of their eyes-fone at thetop of,

the impeller and the other at the bottomis of greatimportanee inthe prevention of air locks. ,g K,

t is a chamber Isituated above the suction port and ,in communication'therewith. It is also placed in communication with the ves-l which by means of the duct v communicates with the chamber t. The object of the noz-` zle and ductis the extraction of any air whichl collects by vortexaction at the eye of the impeller. This air rises through the duct v and passes away by the lpipe g.

If the vacuunr in the vessel which is being drained or drawn from is not constant throughout, 4it isdesirable that the pipe q be ledtothat part or place in the vessel at which the highest vacuum exists.

What we claim is l. A centrifugal pump compri-sing a casing, a vertically arranged shaft mounted therein, a first-stage impeller located at the bottom of said casing, a second-stage impeller located above" said firstjstage impeller, said impellers each having radially extending discharge openings and being jointly con- ',nected to said shaft, said first-stage impeller having an eye located at the top thereof,` Qsaid second-stage impeller having an eye located at the bottoni thereof, and means of communication e'Xtending'in anupward and `radially inward direction between the discharge openings of .thelirststageimpeller and the'eye of the second-'stage impeller.

2. centrifugal pump having a vertical axis of rotation and comprising a first-stage impeller located at the bottom of the pump, thc eye of this impellerbeingat the top thereof, a second-stage impeller located above the said lirst-stage.impeller, the eye of this impeller being at the bottom thereof, a chamber located above the said first-stage impeller and in communication with the eye of this impeller, andabalance pipe connecting the said chamber 'with the vessel which is being drained or drawn from. Y

aXis of rotation and comprising a first-stage impeller located at. the bottom of the pump, the eye of this impeller being at the top thereof a second-stage impeller located .above the said first-stage impeller, the eye of this impeller being at the bottom thereof, a chamber located above the said first-stage impeller and in communication/with the eye of this impeller, a balance pipe connecting the said chamber with the vessel which is being drained or drawn from, an annular passage located at the eye of the said lirststage impeller and leading upwardstherefrom, and a duct leading from the said passage to the said chamber. A

We hereby sign our names to this specilication.

JOHN WHITEHEAD WXLSON DRYSDALE.

JOHN YOUNG.

3. A centrifugal pump having a vertical Y 

